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M Berry

Publications and source records attributed to M Berry.

At least 109 records · Page 6Linked to original sources
PubMed1996

Transfer of horseradish peroxidase from oligodendrocyte to axon in the myelinating neonatal rat optic nerve: artefact or transcellular exchange?

In this paper we make the surprising observation that intracellular injection of horseradish peroxidase (HRP) into a single myelinating oligodendrocyte also resulted in localised HRP labelling at the nodes of Ranvier of some axons of the unit. It appeared that HRP had been transferred to the nodal axoplasm from the paranodal loops of the HRP-filled oligodendrocyte. Three HRP-filled oligodendrocytes from isolated optic nerves of 14-day-old rats were analysed by serial section electron microscopy, and HRP was observed in the axonal cytoplasm at three of the nodes of Ranvier delineated by one of the cells. At labelled nodes, HRP was of a uniform intensity throughout the nodal axoplasm. Axonal labelling gradually diminished along the paranodal regions and was not evident in the contiguous internodal axoplasm beyond 20 microns from the node. The myelin sheaths, paranodal loops, and axons appeared normal at labelled nodes, and the paranodal loops and astrocyte perinodal processes adjacent to those of the HRP-filled oligodendrocyte unit did not contain HRP. There was no evidence of extracellular HRP or tissue damage in the surrounding neuropil, and axons neighbouring those enwrapped by the HRP-filled oligodendrocyte did not contain HRP. The possibility that axonal labelling was an artefact of either iontophoretic injection or tissue preparation is discussed. This provocative finding is not definite proof of exchange, but the balance of evidence supports the possibility that there was transcellular exchange of HRP at paranodes between the labelled oligodendrocyte and some of the axons in the unit. The rarity of HRP transfer to axons suggests that it may be a transient or labile event. It is not clear whether oligodendrocyte to axon macromolecular exchange has real physiological and/or pathological significance.

Animals↗
PubMed1996

An in vitro model of the rat dorsal root entry zone reveals developmental changes in the extent of sensory axon growth into the spinal cord.

The dorsal root entry zone (DREZ) forms the junction between the dorsal roots of the peripheral nervous system and the spinal cord. In rats older than 1 week, lesioned primary sensory axons regenerate within the dorsal roots but stop at the DREZ, and are thus unable to reconnect with the spinal cord. To analyze the causes of this failure, we have developed a culture model of the interaction of sensory axon growth cones with the intact DREZ, whereby dissociated dorsal root ganglion neurons from rats of various ages are grown on longitudinal cryosections of rat spinal cord, incorporating the DREZ and attached dorsal roots, from neonatal, 1-week-old (P6), or adult animals. Neurites of all ages grew along the roots to the DREZ, where their ability to cross into the spinal cord depended on both their age and that of the spinal cord substrate. Neurites from neonatal neurons failed to cross either the P6 or adult DREZ, but a substantial proportion crossed the immature neonatal DREZ. Early embryonic neurites exhibited substantial crossing on both immature and adult DREZ. These findings strongly suggest that soon after birth, the normal mammalian DREZ acquires growth inhibitory activity that is recognized by the axons of postnatal but not early embryonic sensory neurons.

Age Factors↗
PubMed1996

Peripheral nerve explants grafted into the vitreous body of the eye promote the regeneration of retinal ganglion cell axons severed in the optic nerve.

We have conducted experiments in the adult rat visual system to assess the relative importance of an absence of trophic factors versus the presence of putative growth inhibitory molecules for the failure of regeneration of CNS axons after injury. The experiments comprised three groups of animals in which all optic nerves were crushed intra-orbitally: an optic nerve crush group had a sham implant-operation on the eye; the other two groups had peripheral nerve tissue introduced into the vitreous body; in an acellular peripheral nerve group, a frozen/thawed teased sciatic nerve segment was grafted, and in a cellular peripheral nerve group, a predegenerate teased segment of sciatic nerve was implanted. The rats were left for 20 days and their optic nerves and retinae prepared for immunohistochemical examination of both the reaction to injury of axons and glia in the nerve and also the viability of Schwann cells in the grafts. Anterograde axon tracing with rhodamine-B provided unequivocal qualitative evidence of regeneration in each group, and retrograde HRP tracing gave a measure of the numbers of axons growing across the lesion by counting HRP filled retinal ganglion cells in retinal whole mounts after HRP injection into the optic nerve distal to the lesion. No fibres crossed the lesion in the optic nerve crush group and dense scar tissue was formed in the wound site. GAP-43-positive and rhodamine-B filled axons in the acellular peripheral nerve and cellular peripheral nerve groups traversed the lesion and grew distally. There were greater numbers of regenerating fibres in the cellular peripheral nerve compared to the acellular peripheral nerve group. In the former, 0.6-10% of the retinal ganglion cell population regenerated axons at least 3-4 mm into the distal segment. In both the acellular peripheral nerve and cellular peripheral nerve groups, no basal lamina was deposited in the wound. Thus, although astrocyte processes were stacked around the lesion edge, a glia limitans was not formed. These observations suggest that regenerating fibres may interfere with scarring. Viable Schwann cells were found in the vitreal grafts in the cellular peripheral nerve group only, supporting the proposition that Schwann cell derived trophic molecules secreted into the vitreous stimulated retinal ganglion cell axon growth in the severed optic nerve. The regenerative response of acellular peripheral nerve-transplanted animals was probably promoted by residual amounts of these molecules present in the transplants after freezing and thawing. In the optic nerves of all groups the astrocyte, microglia and macrophage reactions were similar. Moreover, oligodendrocytes and myelin debris were also uniformly distributed throughout all nerves. Our results suggest either that none of the above elements inhibit CNS regeneration after perineuronal neurotrophin delivery, or that the latter, in addition to mobilising and maintaining regeneration, also down regulates the expression of axonal growth cone-located receptors, which normally mediate growth arrest by engaging putative growth inhibitory molecules of the CNS neuropil.

Animals↗
PubMed1996

Hyperopia correction by noncontact holmium:YAG laser thermal keratoplasty. Clinical study with two-year follow-up.

BACKGROUND: Thermal keratoplasty to correct hyperopia has been attempted with nonlaser and laser devices. Problems have included long-term regression and irregular induced astigmatism. The present clinical study was performed to investigate the safety, efficacy, and stability of a noncontact mode of holmium: YAG laser energy delivery and a modified laser thermal keratoplasty treatment procedure for correction of low hyperopia. METHODS: Seventeen patients underwent noncontact holmium: YAG laser thermal keratoplasty in their nondominant eyes for correction of hyperopia of up to 3.00 diopters. Treatment parameters included simultaneous delivery of eight holmium: YAG laser spots in a symmetrical octagonal array with a centerline diameter of 6mm, 10 pulses of laser light at 5-Hz pulse repetition frequency, and pulse energies of 159 to 199mJ. Follow-up was 2 years in 15 of 17 patients. RESULTS: In the 15 eyes examined at 2 years after surgery, mean uncorrected distance Snellen visual acuity improved from 20/125-1 to 20/50-2. The mean change in spherical equivalent of subjective manifest refraction was -0.79 diopter. Eleven of these 15 eyes (73%) had a mean refractive correction of -1.1 diopters (range, -0.38 to -2.63 diopters); regression between 14 days and 2 years was 0.2 diopter. Four eyes (27%) had no persistent refractive correction (within +/- 0.25 diopter). Mean induced refractive astigmatism was 0.18 diopter. None of the eyes lost two or more lines of spectacle-corrected distance vision. The amount of refractive correction at 2 years after surgery was correlated to the treatment pulse energy and the volume of the opacified corneal tissue observed immediately after treatment. CONCLUSIONS: This technique of noncontact laser thermal keratoplasty produced safe, effective, and persistent corrections of low hyperopia in the majority of treated eyes.

Aged↗
PubMed1996

Computed tomography morphology of the adrenal glands of patients with Addison's disease.

To study the morphology of the adrenal glands of patients with Addison's disease an ultrasound and a computed tomographic scan of the adrenal glands were performed in 28 patients with Addison's disease. Thirteen patients had bilateral, asymmetric adrenal enlargement. In six of these patients, areas of necrosis and calcification were also seen. Six patients had atrophic glands with calcification and nine patients had normal/atrophic glands without calcification. After instituting appropriate treatment, computed tomography (CT) was repeated between 6 months and 3 years later in 10 of the 13 patients with adrenal enlargement. A reduction in gland size was noted in all patients and one had functional recovery. We conclude that the appearance of the adrenal glands on CT depends not only on the nature of the underlying disease but also on the duration of the illness and the type of treatment.

Addison Disease↗
PubMed1996

Mesenteric plexiform neurofibroma: computed tomography appearance.

Gastrointestinal involvement in von Recklinghausen's disease is usually in the form of neurofibromas and leiomyomas. Very rarely, plexiform neurofibromas may be seen involving the bowel wall and myenteric plexus with secondary minor involvement of the mesentery. This report describes the computed tomography morphology of a plexiform neurofibroma extensively involving the mesentery with minor involvement of the bowel wall.

Child↗
PubMed1996

Effect of glucose on uptake of radiolabeled glucose, 2-DG, and 3-O-MG by the perfused rat liver.

In the transition from the fasting to the fed state, plasma glucose levels rise, and the liver converts from an organ producing glucose to one of storage. To determine the effect of glucose on hepatic glucose uptake, radiolabeled glucose, 2-deoxyglucose, and 3-O-methylglucose were injected into perfused rat livers during different nontracer glucose levels, and the concentrations in the outflow were measured. A mathematical model was developed that described the behavior of the injected compounds as they traveled through the liver and was used to simulate and fit the experimental results. The rates of membrane transport, glucokinase, glucose-6-phosphatase, and the consumption of glucose 6-phosphate were estimated. Membrane transport for all of the tracers decreased as nontracer glucose increased, demonstrating competitive inhibition of the glucose transporter. In contrast, the consumption of injected [2-14C]glucose increased when glucose was elevated, demonstrating that glucose caused an activation of enzyme activity that overcame the competitive inhibition of transport and phosphorylation. When glucose was elevated, the rate coefficient of glucokinase did not decrease, indicating that glucokinase was stimulated by glucose. Both changes would lead to the increased glycogen synthesis and decreased glucose production rate observed in vivo during the fasted-to-fed transition.

3-O-Methylglucose↗
PubMed1996

Polydispersity of normal human conjunctival mucins.

PURPOSE: To isolate all constituent mucins from human conjunctival mucus. METHODS: Mucins were extracted from human conjunctiva in guanidine hydrochloride and protease inhibitors. The mucins were isolated by density gradient centrifugation, gel filtration, and ion exchange chromatography. Throughout purification, the mucin profile was monitored by agarose electrophoresis and vacuum blotting. Blots were probed for peptide and carbohydrate epitopes. The latter included IE3 and TKH2 specific for Tn and sialyl-Tn, respectively, considered tumor-related antigens. In vivo impression cytology specimens of normal conjunctival goblet cells also were probed with the same reagents. Oligosaccharides were released from isolated mucins by alkaline beta-elimination and then size fractionated. RESULTS: Human conjunctival mucins consist of at least three size populations; the largest is excluded on Sepharose CL2B. The two largest populations are polydisperse. Their overall electrophoretic pattern is conserved between individuals. Similar charge distributions were detected in different buoyant density ranges from the density gradient centrifugation: a less charged population containing three components and a highly charged population with two components on agarose electrophoresis. Cross-reaction with IE3 and TKH2 was detected throughout purification in the largest mucins, which were presumably mature, and in impression cytology. Oligosaccharides from mucins in each buoyant density were largely in the monosaccharide and disaccharide range, consistent with Tn and sialyl-Tn standards. CONCLUSIONS: Secreted human conjunctival mucins are polydisperse, with discrete components appearing consistently in pooled and individual samples. They have a unique oligosaccharide pattern containing Tn and sialyl-Tn. This indicates normal roles in normal human ocular mucins for these antigens, which are disease markers in other tissues.

Adult↗
PubMed1996

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Computer Communication Networks↗
PubMed1995

A comprehensive analysis of the distribution of FGF-2 and FGFR1 in the rat brain.

We have examined the cellular distribution of both FGF-2 and FGFR1 immunoreactivity and their mRNAs throughout the normal adult rat brain in order to reconcile numerous disparate findings in the published literature. The results confirm a widespread distribution of FGF-2 and FGFR1 in the rat brain, and different regions express distinct patterns of FGF-2 and FGFR1 mRNA and protein: neuronal and non-neuronal cells show different subcellular distributions that vary according to the area where they are located. The intensity of the staining and hybridization also varies according to the loci examined and the cell type involved. Astrocytes contain the highest levels of FGF-2 and FGFR1 mRNAs, and characteristically, possess high levels of immunoreactive FGF-2 within the nucleus. Amongst non-neuronal cells, oligodendrocytes do not synthesize or contain significant levels of FGF-2 immunoreactivity however, they do express FGFR1 mRNA. In these cells, immunoreactive FGFR1 is mainly associated with the myelin sheaths of neuronal fibers. In ventricular systems, ependymal cells synthesize and contain immunoreactive FGFR1. In contrast, only cells lining the lateral wall of the IIIrd ventricle express FGF-2 mRNA. Subependymal cells contain high levels of both FGF-2 and FGFR1 immunoreactivity. Neurons express low levels of FGF-2 mRNA and immunoreactive FGF-2 is localized predominantly to the perikaryon. However, selected populations of neurons, such as CA2 field of the hippocampus, show high levels of FGF-2 mRNA, in which the nucleus is strongly immunopositive. Similarly, high levels of FGFR1 mRNA are localized to select populations of neurons (e.g. amygdala). FGFR1 immunoreactivity is mainly associated with myelinated fiber tracts (e.g. striatum), and some neurons show immunoreactivity in the perikaryon (e.g. hippocampus), the nucleus (e.g. mesencephalic trigeminal nucleus), or in axonal projections (e.g. hypothalamus). Remarkably, in many of the areas studied, FGF-2 and FGFR1 mRNA and/or their translated protein do not co-localize in neurons (e.g. neo-cortices) or even in the same regions of the brain (e.g. substantia nigra). In other instances, mRNAs for both FGF-2 and FGFR1 colocalize (e.g. supraoptic nucleus). The brain, in contrast to peripheral tissues, contains high levels of FGF-2 and actively expresses its gene under normal physiological conditions. The highly specific anatomical distribution of immunoreactive FGF-2 in neuronal and non-neuronal brain cells, supports the notion that it plays a multifunctional role in the CNS under normal physiology. By correlating the localization and the synthesis of FGF-2 and one of its high affinity receptors, FGFR1, in the CNS, it should be possible to obtain a better understanding of the roles of FGF-2 in normal and pathological conditions.

Animals↗
PubMed1995

Biochemical subtypes of oligodendrocyte in the anterior medullary velum of the rat as revealed by the monoclonal antibody Rip.

Oligodendrocytes were studied in the anterior medullary velum (AMV) of the rat using the monoclonal antibody Rip, an oligodendrocyte marker of unknown function. Confocal microscopic imaging of double immunofluorescent labelling with antibodies to Rip and carbonic anhydrase II (CAII) revealed two biochemically and morphologically distinct populations of oligodendrocyte which were either Rip+CAII+ or Rip+CAII-. Double immunofluorescent labelling with Rip and myelin basic protein (MBP) or glial fibrillary acidic protein (GFAP) provided direct evidence that Rip-labelled cells were phenotypically oligodendrocytes and confirmed that Rip did not recognise astrocytes. Oligodendrocytes which were Rip+CAII+ supported numerous myelin sheaths for small diameter axons, whilst Rip+CAII- oligodendrocytes supported fewer myelin sheaths for large diameter axons. Morphologically, Rip+CAII+ oligodendrocytes corresponded to types I or II of classical nomenclature, whilst Rip+CAII- oligodendrocytes corresponded to types III and IV. The results demonstrated a biochemical difference between oligodendrocytes which myelinated small and large diameter fibres.

Animals↗
PubMed1995

Axon-glial relationships in the anterior medullary velum of the adult rat.

The anterior medullary velum is a thin sheet of CNS tissue which roofs the rostral part of the IVth ventricle and contains fascicles of myelinated fibres which, in part, arise from the nucleus of the IVth cranial nerve. This study used histochemical, immunohistochemical, and intracellular dye-injection techniques to describe cellular interrelationships in the velum in whole-mounts and in sections. Rip antibody-stained whole mounts provided a unique description of both oligodendrocyte units (defined as an oligodendrocyte and the complement of myelinated internodal segments it forms), and consecutive myelin sheaths along the same axon. A broad range of unit morphologies was categorised into four arbitrary groups, according to classical criteria, which comprised small cells supporting the short, thin myelin sheaths of 15-30 small diameter axons (Type I), through intermediate types (II & III), to the largest cells forming the long, thick myelin sheaths of 1-3 large diameter axons. Rip antibody and ferric ion-ferrocyanide staining, together with intracellular dye injection, revealed oligodendrocyte process branching patterns and their mode of engagement of myelin sheaths, nodes of Ranvier, and the spatial disposition of the outer cytoplasmic rims of myelin sheaths. The latter formed a conspicuous spiral ridge on the exterior surface of myelin sheaths which connected with the paranodal loops at each heminode. Large bundles of axons decussated through the velum, the bulk of which were IVth nerve fibres which constituted the IVth nerve rootlet. The PNS/CNS transitional zone of the IVth nerve was located 0.25-0.50 mm along the root, where astrocytic end-feet defined an abrupt margin, convex towards the periphery, where the heminodes of central and peripheral myelin were apposed, and where the basal lamina tubes of the Schwann cell units were discontinued. The basal processes of ependymal cells lining the ventricular wall of the velum, passed between axon bundles before abutting on the basal lamina of the pia. Many of these processes branched and ran along the axonal bundles. A monolayer of microglia occupied a subependymal stratum in which the non-overlapping dendritic territories of each cell formed a regular mosaic throughout the velum without any obvious interaction with either axons or other glial cells. Astrocytes were also uniformly distributed; their fine processes made up a dense lattice amongst axons, often running parallel and within the fibre bundles; stouter ones had terminal end-feet which undercoated the basal lamina of both the glia limitans externa and the blood vessels in the velum.

Animals↗
PubMed1995

Ossified gastric leiomyoma in a child: a case report.

Calcification in gastric leiomyoma (GLM) is extremely rare. Eleven cases have been reported so far, all in adults. We report the first ossified GLM in a 2-year-old child. A number of unusual clinical and imaging features are discussed.

Calcinosis↗
PubMed1995

Relationship between myelin sheath diameter and internodal length in axons of the anterior medullary velum of the adult rat.

Relations between myelin sheath diameters and internodal lengths were measured in whole mounts of osmium stained intact anterior medullary velum (AMV) from glutaraldehyde perfused adult rats. The AMV is a sheet of CNS tissue which roofs the IVth ventricle and contains fascicles of myelinated fibres which arise mainly from the nucleus of the IVth cranial nerve. These fibers displayed a broad range of myelin sheath external diameters and internodal lengths, from < 1-12 microns and 50-750 microns, respectively. Myelin sheath external diameter was a measurement of the axonal diameter plus the thickness of its myelin sheath, while internodal length was measured as the distance between consecutive nodes. There was a broadly linear relationship between myelin sheath diameters and internodal lengths, with the smaller diameter sheaths tending to have shorter internodes than the larger. However, the correlation was weak and for any given diameter myelin sheaths displayed considerable variation in their internodal lengths. The smallest diameter myelin sheaths, < 4 microns, consistently had shorter internodes than predicted by a linear regression and, in an analysis of consecutive internodes in single fibres, the slope was flattened in fibres with a diameter > 4 microns. Our results indicated that small and large calibre fibres may have different myelin sheath diameter-internodal length interrelations.

Animals↗
PubMed1995

Toxicity of antibiotics and antifungals on cultured human corneal cells: effect of mixing, exposure and concentration.

Toxic effects of topical drugs may be masked by manifestations of the disease they cure. The toxicity of drug mixtures has not been thoroughly studied. We therefore investigated cytopathic effects on primary cultures of human corneal cells of six topical antimicrobials singly and in combinations of any two, to determine the combined toxicity ranking and the interaction between duration of exposure and concentration. Preconfluent cultures were exposed to fixed dilutions of single drugs, or to equal-dilution mixtures of two drugs, for 7 and 14 days. Diminishing concentrations of single drugs were applied sequentially to cultures for 14 days. The number of metabolically competent cells was assessed by measuring hexosaminidase and total protein. Toxic effects depended on substance, concentration and exposure. The scale of toxicity determined for single drugs after 7 days of exposure was: gentamicin > econazole > or = methicillin > or = clotrimazole > or = miconazole > or = chloramphenicol. After 14 days this order changed: in particular chloramphenicol showed a highly increased toxicity. The order of diminishing effects was: gentamicin > chloramphenicol > or = methicillin > miconazole > econazole > clotrimazole. A clear reduction in cytopathic effects was observed when drug concentration was decreased progressively only in cultures treated with gentamicin or methicillin. All drug combinations were more toxic than their components at equal dilution. Combinations containing chloramphenicol ranked most toxic overall, those containing econazole least. A tapering off combination regime did not improve cell survival. These in vitro toxicity data complement clinical studies and suggest ways in which topical drugs can be chosen to minimise toxic effects to corneal surface.

Anti-Bacterial Agents↗